Obgyn Key

The nervous system consists of three main regions: • The central nervous system (CNS) consists of the brain and spinal cord and is protected by the cranium and vertebral column….

The cardiovascular system is the first major system to function in the embryo. The primordial heart and vascular system appear in the middle of the third week ( Fig. 13.1…

The urogenital system is divided functionally into two different embryologically component parts: the urinary system and the genital system . The urogenital system includes all the organs involved in reproduction…

Birth defects (anomalies) are developmental disorders present at birth. Defects are the leading cause of infant mortality (fetal outcome). They may be structural, functional, metabolic, behavioral, or hereditary. Birth defects…

Development of Eyes and Related Structures 17 The eyes begin to develop in 22-day embryos when optic grooves appear ( Fig. 18.1 A and B ). The eyes are derived…

The integumentary system consists of skin and its appendages: sweat glands, nails, hairs, sebaceous glands, arrector muscles of hairs (arrector pili muscles), mammary glands, and teeth. Development of Skin and…

During the process of embryonic development, undifferentiated precursor cells differentiate and organize into the complex structures found in functional adult tissues. This intricate process requires cells to integrate many intrinsic…

T he pharyngeal apparatus consists of pharyngeal arches, pouches, grooves, and membranes ( Fig. 9.1 ). These early embryonic structures contribute to the formation of the face and neck. Fig….

Early Stages of Limb Development 15 The upper limb buds are visible by day 24, and the lower limb buds appear 1 or 2 days later, with the activation of…

T he alimentary system (digestive system) is the digestive tract from the mouth to the anus, with all its associated glands and organs. The primordial gut forms during the fourth…